Technical Abstract:
Leafy spurge (Euphorbia esula L.) is a noxious invasive weed that infests over 1.2 million hectares of land in North America. One of the fundamental needs in leafy spurge management is cost-effective, large-scale, and long-term documentation and monitoring of plant populations. Leafy spurge is a good candidate for detection via remote sensing because the distinctive yellow-green color of its bracts is spectrally unique when compared to co-occurring green vegetation. During 1999, Airborne Visible / Infrared Imaging Spectrometer (AVIRIS) imagery were acquired in northeastern Wyoming and ground vegetation data were collected nearby Devils Tower National Monument in Crook County, Wyoming. Hyperspectral analyses were used to classify leafy spurge presence/absence; overall accuracy was 95%. Landsat ETM+ and SPOT 4 imagery had maximum classification accuracies of 66%. The classification data were used to test the Weed Invasion Susceptibility Prediction (WISP) model, which uses available geospatial data layers to predict the potential distribution of various invasive weeds. For the area covered with AVIRIS imagery, leafy spurge was predicted to infest 23% of the area, whereas the actual occurrence was 8% of the area, almost one-third of the predicted potential area. There were problems testing WISP predictions with remote sensing data because of positional inaccuracies, but the tests were more comprehensive than ground-based sampling.